JPH0671557A - Polishing method of crystal and polishing jig - Google Patents

Abstract

PURPOSE:To shorten a span of machining time in checking the stock removal of a polished body to the minimum by setting up an eccentric load weight on a plane at the opposite side of the plane of a polished body carrier where a dummy body thicker than the polished body. CONSTITUTION:When a polished body 3 and a dummy body 2 both are set to a polished body carrier 1, this dummy body 2 adjusted so as to make its polished surface thicker than a polished surface of the polished body 3 is set up around the polished body 3, and an opposed surface of the polished surface of the polished body 3 is parallelly set to a plane of the polished body carrier 1. Next, using an eccentric load weight 5, the polished surface of the dummy body 2 and the plane of the carrier 1 are polished so as to make them become paralleled. Subsequently, the polished body 3 is polished to the desired thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polishing a crystal substrate and a polishing jig used for carrying out this method.
In particular, it is a polishing jig that is suitable for obtaining a highly accurate optical device in which the variation in the parallel flatness of the substrate is small, and a polishing method using this jig.

[0002]

2. Description of the Related Art In general, surface polishing of a crystalline substrate or a thin film used for electronic parts and optical parts is performed by Kasai, Noda and Ida: Precision processing of lithium tantalate electro-optical element, Research Practical Report, Vol. As shown in p915 (1971), a glass carrier 1 to be polished is used as a polishing jig, and a substrate 3 to be polished and a dummy plate 2 having the same height are polished on the lower surface of the carrier 1 to be polished. Waxes 4 are fixed and adhered around the body 3, respectively, and are brought into contact with the surface plate 10 while applying a load from the upper portion of the carrier 1 to be polished for polishing (see FIG. 3).

[0003]

To be described with reference to FIG. 3, in FIG. 3A, an eccentric load weight 5 is provided so that the polished surface of the dummy bodies 2-1 and 2-2 and the flat surface of the polished carrier 1 are parallel to each other.
Polishing is performed to make a so-called dummy body parallel.
After the surface to be polished of the dummy body and the plane of the carrier 1 to be polished are parallel to each other, the body 3 to be polished is polished by using the uniform weight 9 as shown in (b). However, since the object to be polished and the dummy body have substantially the same height, the object to be polished is also polished when the dummy body is parallelized. Therefore, if such polishing is performed, the object to be polished is scraped more than necessary. Furthermore, in order to shorten the processing time for parallelizing the dummy body, a large abrasive grain is used. However, in this conventional method, the workpiece to be polished is damaged when the dummy body is parallelized. Therefore, it is necessary to make the abrasive grains small, which requires a lot of time. Also,
Since the parallelism of the dummy body is not reproducible, the amount of polishing processing is not reproducible.

When the dummy body is first attached and the dummy body is parallelized and then the object to be polished is fixed with wax, the wax is melted by heating again when fixing the object to be polished with wax. However, there is a drawback that the parallelism of the dummy body is lowered.

An object of the present invention is to overcome the above-mentioned drawbacks of the prior art. In addition, the polishing amount of the object to be polished can be minimized, the processing time can be shortened, and the thickness of the crystal can be reproducible and uniform. The object of the present invention is to provide a polishing method capable of obtaining a body and a polishing jig used for the method.

[0006]

As a result of earnest research for achieving the above object, the inventors of the present invention used a dummy body thicker than an object to be polished as a polishing jig, and It has been found that by bonding the to a carrier to be polished and polishing the dummy body to make it parallel, the parallelism of the dummy body can be obtained without damaging the body to be polished.

That is, the polishing jig of the present invention comprises a carrier to be polished, a dummy body thicker than the body to be polished, and an eccentric load weight. The thickness of the dummy body is 10 to 500 μm, more preferably 50, than the thickness of the body to be polished.
It is desirable that the thickness is about 100 μm.

Further, in the polishing method of the present invention, a dummy body is adhered to the plane of the carrier to be polished and an eccentric load weight is used so that the surface to be polished of the dummy and the plane of the carrier to be polished are parallel to each other. It is a method of correcting by polishing, and then polishing the object to be polished by using a uniform load weight if necessary. In the method of polishing the object to be polished,
When the object to be polished and the dummy body are bonded to the carrier to be polished, the surface to be polished is 10 to 500 more than the surface to be polished of the object to be polished.
A dummy body, which is adjusted to have a thickness of about μm, more preferably about 50 to 100 μm, is arranged around the object to be polished, and the opposite surface of the object to be polished is bonded in parallel to the plane of the carrier to be polished. It is advantageous to do

[0009]

The polishing jig of the present invention, as shown in FIG. 1, has a carrier 1 to be polished having flat surfaces whose both surfaces are parallel to each other, and surrounds the periphery of the object to be polished and is arranged on the plane of the carrier to be polished. Desirably 10 to 500 μm than the object to be polished
The dummy body 2 has a relatively large thickness, and the eccentric load weight 5 is disposed on the plane opposite to the plane of the carrier to be polished on which the dummy body is disposed. The dummy body 2 arranged around the object to be polished 3 is preferably ring-shaped,
It is desirable to be thicker than the object to be polished by about 10 to 500 μm. This is because if it is larger than 500 μm, it takes time to polish the dummy body, and if it is less than 10 μm, parallel alignment cannot be completed while polishing the dummy body. The thickness of the dummy body is 50 to 100 μm larger than the thickness of the object to be polished.
It is advantageous to be thick.

The polishing method will be specifically described with reference to FIG. The object to be polished 3 and the dummy body 2 are the object to be polished carrier 1
Then, it is bonded with wax 4 (a in FIG. 1). At this time,
It is desirable to form the flat surface 6 by smoothing the facing surface of the object to be polished 3 by polishing or the like, if necessary. Further, when adhering, the facing surface 6 of the surface to be polished of the object to be polished is corrected so as to be bonded in parallel to the plane 7 of the carrier to be polished. That is, the thickness of the object to be polished is measured at several points with a height gauge before adhering, and after adhering to the object to be polished carrier 1, the height of the same point is measured so that the wax 4 has a uniform thickness. Make corrections.

Then, the eccentric load weight 5 is used for polishing so that the surface 8 to be polished of the dummy body 2 and the plane of the carrier 1 to be polished are parallel to each other (b in FIG. 1). That is, FIG. 1 (b)
When the height of the point a from the plane 7 of the carrier to be polished is higher than the points b and c, X of the eccentric load weight of FIG.
The portion is polished so that it corresponds to the point A in FIG. 1 (b). After the surfaces 8 to be polished of the dummy body are all at the same height and parallel to 7, the weight 9 is evenly loaded if necessary.
The dummy body 2 and the body 3 to be polished are polished by using (c in FIG. 1). By such a polishing method, the dummy body 2 can be polished and the parallelism can be corrected without damaging the workpiece 3. Further, since it is possible to change the abrasive grains when polishing the dummy body and the body to be polished, it is necessary to use large abrasive grains for polishing the dummy body and small abrasive grains for polishing the body to be polished. it can. Therefore, the polishing time can be shortened. Furthermore, it is possible to reproducibly produce a crystal body having a uniform thickness.

As the carrier to be polished, a fixing jig made of alumina having a diameter of 138 mm and a parallel flatness of 0.3 μm or less is suitable.

The dummy body 2 may have the same hardness as the body 3 to be polished, and may be alumina, silicon carbide, silicon oxide, zirconia, silicon nitride, glass or the like. LiTaO
_{3 When} polishing a substrate or the like, a glass having a Mohs hardness of 6 to 7 is desirable in terms of characteristics and economy, and a shape that surrounds the object to be polished in a ring shape is desirable.

The abrasive-platen used in the polishing method of the present invention is preferably as follows. When polishing the dummy body, a diamond slurry having a particle diameter of 2 μm and a copper kemet disk are used. And for polishing the object to be polished, the particle size is 1/4 μ
m diamond slurry, tin-lead kemet board is used for polishing. Changing the abrasive grains and the kemet board is
For the following reasons. When polishing the dummy body, it is possible to shorten the processing time by increasing the polishing rate, and when polishing the body to be polished, scratches due to polishing can be minimized. The abrasive grain-surface plate is changed when the height difference between the object 3 to be polished and the dummy 2 becomes about several μm. This is because a large lap mark is not generated on the object to be polished 3.

The parallelism is measured by using a height gauge,
It is possible to measure up to 1 μm. When the thicknesses of the dummy body 2 and the body to be polished 3 fixed to the body carrier 1 to be polished are all the same, the parallelism is 1 μm / 138 mm or less.

The flatness is measured by using an optical flat (λ = 0.54 μm) with an accuracy of λ / 20. If the interference fringes are parallel, the flatness of the object to be polished 3 is 0.54 / 20 =
It is 0.027 μm or less. The case where the object to be polished 3 is adhered to the carrier 1 by the wax 4 and the object to be polished 3
If the interference fringes are the same when the is removed, there is no adhesive distortion and the flatness is 0.027 μm or less.

[0017]

EXAMPLES The specific method of the present invention will be described below, but the present invention is not limited to these examples.

Example 1 A LiTaO ₃ substrate 3 (diameter 20 mm, thickness 1 mm) was polished and parallelized. Outer diameter 4 as dummy body 2
A ring-shaped glass plate having a size of 6 mm, an inner diameter of 23 mm and a thickness of 1.1 mm was used. Workpiece carrier 1 (diameter 138m
m, parallel flatness 0.3 μm or less) LiTaO ₃ substrate 3
And the dummy body 2 was adhered by the wax 4. At this time, the facing surface 6 of the surface to be polished of the object to be polished 3 was corrected so as to be bonded in parallel to the plane 7 of the carrier to be polished.
That is, the thickness of the object to be polished is measured at several points with a height gauge before adhering, and after adhering to the object to be polished carrier 1, the height of the same point is measured so that the wax 4 has a uniform thickness. Made a correction. While polishing the dummy body 2, the eccentric load weight 5 shown in Table 1 is used so that the polished surface 8 of the dummy body 2 and the flat surface 7 of the polished carrier 2 are parallel to each other. Was fixed. If the heights of the dummy bodies 2 are all the same, the parallelism is 1 μm / 13.
It is 8 mm or less. After the parallelism reached the target value, a uniform load weight 9 (true casting, mass 3.1 kg) was applied and polished. A diamond slurry having a particle diameter of 2 μm and a copper kemet disk are used for polishing the dummy body, and when the difference in thickness between the dummy body 2 and the object to be polished 3 is several μm, the grain size is 1 μm.
Polished using a / 4 μm diamond slurry, tin-lead kemet board. After the entire surface of the object to be polished 3 is polished,
Optical flat with accuracy λ / 20 (λ = 0.54μ
When the flatness was measured by m), the interference fringes were parallel. When the object 3 to be polished was removed from the object carrier 1 to be polished and the flatness was measured again, the interference fringes were the same.
In this way, when the polishing amount of the object to be polished is 7 μm, the parallelism is 1 μm.
Li with m / 138 mm or less and flatness of 0.027 μm or less
A TaO ₃ substrate was obtained. The time required for processing was 16 hours. Similar methods result of polishing the LiTaO ₃ substrate at a thickness of 993 ± 1 [mu] m of LiTaO ₃ substrate, parallelism 1 [mu] m / 138 mm or less, to give the following LiTaO ₃ substrate flatness 0.027.

Example 2 The LiNbO ₃ substrate 3 (15 × 15 mm, thickness 1 mm) was also polished in the same manner as in Example 1. As the dummy body 2, a ring-shaped glass body having a thickness of 1.06 mm was used. The LiNbO ₃ substrate 3 and the dummy body 2 were bonded to the carrier 1 to be polished. At this time, the facing surface 6 of the surface to be polished of the object to be polished 3 was corrected so as to be bonded in parallel to the plane 7 of the object to be polished carrier 1. After that, the dummy body 2 was polished while the surface 8 of the dummy body 2 and the plane of the body carrier 1 to be polished were adjusted to be parallel. If the heights of the dummy bodies 2 are all the same, the parallelism is 1 μm / 13.
It is 8 mm or less. After the parallelism reached the target value, polishing was performed using the uniform load weight 9. After the entire surface of the LiNbO ₃ substrate 3 was polished, when the flatness was measured with an optical flat (λ = 0.54 μm) with an accuracy of λ / 20, the interference fringes were parallel. And LiNbO ₃ substrate 3
The interference fringes were the same when the sample was removed from the carrier 1 to be polished and the flatness was measured again. In this way, the parallelism of 1 μm / 138 mm or less when the polishing amount of the workpiece 3 is 5 μm,
A LiNbO ₃ substrate having a flatness of 0.027 μm or less was produced. The time required for processing was 15 hours. In addition, as a result of polishing the LiNbO ₃ substrate three times by the same method,
bO ₃ substrate thickness 995 ± 1μm, parallelism 1μm / 1
LiNbO of 38 mm or less and flatness of 0.027 μm or less
₃ substrates were obtained.

Comparative Example A LiTaO ₃ substrate 3 (diameter 20 mm, thickness 1 mm) was polished. The dummy body 2 has an outer diameter of 46 mm and an inner diameter of 23
A donut-shaped glass plate having a thickness of 1 mm and a thickness of 1 mm was used. Carrier to be polished 1 (diameter 138 mm, parallel flatness 0.
The LiTaO ₃ substrate 3 and the dummy body 2 were bonded to each other with a wax 4 to a thickness of 3 μm or less). At this time, the facing surface 6 of the surface to be polished of the object to be polished 3 was corrected so as to be bonded in parallel to the plane 7 of the object to be polished carrier 1. Then, the eccentric load weight 5 was used to correct the parallelism while polishing. For polishing, a diamond slurry having a particle diameter of 1/4 μm and a tin-lead kemet disk were used. If the heights of the dummy body 2 and the body 3 to be polished are all the same, the parallelism is 1 μm / 1.
It is 38 mm or less. Optical flatness (λ = 0.54 μm) with accuracy λ / 20 after the parallelism reaches the target value
When the flatness was measured by, the interference fringes were parallel. Then, when the object to be polished was removed from the alumina jig and the flatness was measured again, the interference fringes were the same. The polishing amount of the LiTaO ₃ substrate was 82 μm, and the time required for processing was 28 hours. Further, as a result of polishing the LiTaO ₃ substrate three times by the same method, the thickness of the LiTaO ₃ substrate was 940 ± 20.
was μm.

[0021]

As described above, according to the present invention, the polishing amount of the object to be polished can be minimized and the processing time can be shortened. Further, since a thick crystal can be reproducibly polished, it is effective for obtaining a highly accurate optical device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state of a polishing method of the present invention.

FIG. 2 is a diagram showing an eccentric load weight and a uniform load weight according to the present invention.

FIG. 3 is an explanatory view showing a conventional polishing method.

[Explanation of symbols]

 1 Polished Carrier 2 Dummy 3 Polished 4 Wax 5 Eccentric Load Weight 6 Flat Surface Formed on Opposite Surface of Polished Object 7 Flat Surface of Polished Carrier 8 Polished Surface of Dummy 9 Uniform Load Weight 10 surface plate

[Table 1]

Claims (2)

[Claims] 1. A carrier to be polished having (a) both surfaces having planes parallel to each other, and (b) disposed around a target to be polished,
A dummy body thicker than the object to be polished arranged on the plane of the carrier to be polished, (c) an eccentric load weight arranged on a plane opposite to the plane of the carrier to be polished on which the dummy body is arranged, A polishing jig composed of (a) to (c). 2. (a) When adhering an object to be polished and a dummy object to an object carrier, the dummy object is adjusted so that the surface to be polished is thicker than the surface to be polished of the object to be polished. And a step of adhering the opposite surface of the surface to be polished of the object to be polished parallel to the plane of the object carrier. (B) A step of polishing with an eccentric load weight so that the surface to be polished of the dummy body and the plane of the carrier to be polished are parallel to each other. (C) A step of polishing the object to be polished to a desired thickness. A method for polishing a crystal body comprising the steps (a) to (c) above.